GARCH models with leverage effect : differences and similarities

In this paper, we compare the statistical properties of some of the most popular GARCH models with leverage effect when their parameters satisfy the positivity, stationarity and nite fourth order moment restrictions. We show that the EGARCH specication is the most exible while the GJR model may have important limitations when restricted to have nite kurtosis. On the other hand, we show empirically that the conditional standard deviations estimated by the TGARCH and EGARCH models are almost identical and very similar to those estimated by the APARCH model. However, the estimates of the QGARCH and GJR models differ among them and with respect to the other three specications.EGARCH, GJR, QGARCH, TGARCH, APARCH

l-Amino Acid Production by a Immobilized Double-Racemase Hydantoinase Process: Improvement and Comparison with a Free Protein System

Protein immobilization is proving to be an environmentally friendly strategy for manufacturing biochemicals at high yields and low production costs. This work describes the optimization of the so-called “double-racemase hydantoinase process,” a system of four enzymes used to produce optically pure l-amino acids from a racemic mixture of hydantoins. The four proteins were immobilized separately, and, based on their specific activity, the optimal whole relation was determined. The first enzyme, d,l-hydantoinase, preferably hydrolyzes d-hydantoins from d,l-hydantoins to N-carbamoyl-d-amino acids. The remaining l-hydantoins are racemized by the second enzyme, hydantoin racemase, and continue supplying substrate d-hydantoins to the first enzyme. N-carbamoyl-d-amino acid is racemized in turn to N-carbamoyl-l-amino acid by the third enzyme, carbamoyl racemase. Finally, the N-carbamoyl-l-amino acid is transformed to l-amino acid by the fourth enzyme, l-carbamoylase. Therefore, the product of one enzyme is the substrate of another. Perfect coordination of the four activities is necessary to avoid the accumulation of reaction intermediates and to achieve an adequate rate for commercial purposes. The system has shown a broad pH optimum of 7–9, with a maximum activity at 8 and an optimal temperature of 60 °C. Comparison of the immobilized system with the free protein system showed that the reaction velocity increased for the production of norvaline, norleucine, ABA, and homophenylalanine, while it decreased for l-valine and remained unchanged for l-methionine

The influence of social capital on risk-taking propensity. A study on Chinese immigrant entrepreneurs

This paper studies the influence of social capital on immigrant entrepreneurs’ risk-taking propensity. The paper has a particular focus on Chinese immigrants and also explores the effects of the so-called “guanxi”, a specific form of social capital for Chinese communities. The empirical research is based on a survey conducted in 2012 on Chinese immigrant entrepreneurs in Andalusia (Spain). An ordinal logistic regression specification was employed to test the hypotheses. The results show that the Chinese immigrant entrepreneurs with greater structural, relational and cognitive social capital and better “guanxi” have a higher risk-taking propensity in their business activity

Experimental study of MIMO-OFDM transmissions at 94 GHz in indoor environments

Millimeter wave (mm-wave) frequencies have been proposed to achieve high capacity in 5G communications. Although meaningful research on the channel characteristics has been performed in the 28, 38and 60 GHz bands ─in both indoor and short-range scenarios─,only a small number of trials (experiments) have been carried out in other mm-wave bands. The objective of this work is to study the viability and evaluate the performance of the 94 GHz frequency band for MIMO-OFDM transmission in an indoor environment. Starting from a measurement campaign, the performance of MIMO algorithms is studied in terms of throughput for four different antenna configurations.This work was supported in part by the Ministerio de Economía y Competitividad MINECO, Spain under Grant TEC2016-78028-C3-2-P, and in part by the European FEDER funds

Estudio de la Escuela de Espalda de la Universidad de Almería. Ejercicio físico, rendimiento y salud laboral

Objetivo: Evaluar los efectos de la Escuela de Espalda (EE) de la Universidad de Almería en la percepción del rendimiento laboral, de la condición física y la salud raquídea de sus trabajadores cuando acuden al dicho programa. Metodología: Se desarrolló un programa de ejercicio físico con una duración de 3 meses con una frecuencia de 2 días a la semana y 30 minutos por sesión a 56 trabajadores de la Universidad de Almería (n=56), que en su mayoría, tenían algias raquídeas y que formaron el grupo de la Escuela de Espalda. Se realizaron ejercicios de estiramientos (activos y pasivos), de fuerza y de concienciación postural. Los resultados fueron evaluados al final del periodo de intervención mediante un cuestionario autoadministrado. Resultados: Se ha comprobado que los sujetos que participaron en la EE de la Universidad de Almería durante los 3 meses de intervención, mejoraron su percepción en el aumento de la condición física general (81%), en la tonificación muscular (81%), en la autonomía en la realización de los ejercicios (95%), en el cambio de sus hábitos de higiene postural (76%), en la mejora sus aptitudes físicas para la realización de sus funciones laborales (81%), en la influencia positiva para su rendimiento laboral (76%), en la mejora psicológica para afrontar la jornada laboral de manera más positiva (81%); también han comentado las experiencias vividas en la EE con otros compañeros de trabajo (100%), y volverían a la EE (100%). Conclusiones: La EE de la Universidad de Almería ha contribuido positivamente en la mejora de la percepción del rendimiento laboral, en la condición física y la salud de sus trabajadores que participaron en dicho programa

Euskarari buruzko Foru Legearen aplikazioa eta garapena Nafarroako Foru Administrazioan

La primera regulación del uso del euskera en las Administraciones Públicas de Navarra, tras la promulgación en 1986 de la Ley Foral del Vascuence, se produjo con los Decretos Forales 70/1994 y 135/1994. Sin embargo, a partir de 1996 tiene lugar un cambio radical en cuanto a la política sobre el euskera, que culmina con el Decreto 372/2000.Euskarari buruzko Foru Legea 1986an aldarrikatu ostean, 70/1994 eta 135/1994 Foru Dekretuek arautu zuten Nafarroako Administrazio Publikoetan euskararen erabilera. 1996tik aurrera, baina, errotiko aldaketa gertatu zen euskararen politikaren esparruan, 372/2000 Dekretuarekin.La première réglementation de l'usage de l'euskara dans les Administrations Publiques de Navarre, après la promulgation de la Loi Foral du Basque en 1986, ne verra pas le jour publiquement jusqu'aux Decrets 70/1994 et 135/1994. Pourtant, à partir de 1996 survient un changement radical concernant la politique de la langue basque, qui atteint son point culminant avec le Décret 372/2000.The first regulation of the use of the Basque language in the Public Administration of Navarre, after the promulgation of the Law on the Basque Language in 1986, came along with the Decrees 70/1994 and 135/1994. However, as from 1996, there is a radical change concerning Basque language policy that culminates with Decree 372/2000